An XMM-Newton observation of the luminous Seyfert 1 galaxy Markarian 509

We present the spectral analysis of an early XMM-Newton observation of the luminous Seyfert 1 galaxy Mrk 509. We find the hard (2-10 keV) continuum sl ope, including reflection, to be somewhat flatter (Gamma = 1.75) than that of a typical broad-line Seyfert 1 galaxy. The most obvious feature in the h ard X-ray spectrum is a narrow emission line near 6.4 keV with an equivalen t width of similar to 50 eV. The energy and strength of this line is consis tent with fluorescence from "neutral" iron in the molecular torus, and we n ote the emerging ubiquity of this feature in XMM-Newton and Chandra observa tions of Seyfert 1 galaxies over a wide luminosity range. We also find evid ence for a second emission line at 6.7-6.9 keV, which we attempt to model b y reflection from a highly ionized disk. A "soft excess," evident as an upw ard curvature in the continuum flux below similar to 1.5 keV, cannot be exp lained solely by enhanced reflection from the ionized disk. The RGS spectru m shows only weak discrete emission and absorption features in the soft X-r ay spectrum, supporting our conclusion that the soft excess emission in Mrk 509 represents the high-energy portion of optically thick, thermal emissio n from the inner accretion disk.